I'm new to Power BI and exploring the use of Data Marts for large and constantly growing data volumes. My data source for my Data Mart is MS Azure Blob with JSON files (with excess of 100 columns).
I created a Data Mart and connected to the Azure Blob/JSON file successfully - I did not do any modelling. Saved successfully.
I immediately went back into the Data Mart (Transform) to begin the modelling step by step. I filtered only one column (Extension) to only show .json files and tried saving again. On saving the error shown below referring to DataMartVersionMismatch came up when reaching Start data load.
I exited Power Query, went back in and without trying to do any modelling, tried to save right away. The same error was displayed.
Where am I going wrong ?
BTW - I have successfully modelled these JSON files using Power BI Desktop successfully previously in the exact same sequence of steps.
Thank you for any assistance
Solved! Go to Solution.
What is your rationale for shuffling the data from one Azure data storage (BLOB) to another Azure data storage (datamart) ? What prevents you from consuming the BLOB data directly in the dataset?
Hi lbendlin, Thank you for responding
We use JSON files in the Azure Blob, which does not support M Folding. We want to implement incremental refresh which is supported in Datamarts, but not in the Azure Blob with JSON files.
So I did manage to at least save the initial JSON file upload (no data modelling), but the moment I started any data modelling in Power Query, and tried saving, it would crash on me giving the version error or other errors referring to missing columns (columns which actually exist - this makes no sense).
The Power Query in Datamarts appears to be very sensitive and look for things that do not exist.
BTW - these exact JSON files were successfully unpacked on Power BI Desktop and I followed the exact same sequence I used on PBI desktop, but these errors pop up.
We use JSON files in the Azure Blob, which does not support M Folding. We want to implement incremental refresh which is supported in Datamarts, but not in the Azure Blob with JSON files
Incremental refresh does not mandate that the query folds. You can achieve the same with custom queries.
Oh wow ! I was not aware and none of my research covered custom queries as an option.
Do you have a link you could refer me to so that I can explore this in more detail?
Thank you for your assistance - much appreciated
Take a look at the September 2023 Power BI update to learn more.
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